Now, mom Emily France is furious at the way the United Airlines handled the medical crisis.

The 39-year-old mother and her 4-month-old son, Owen, were flying from Denver to El Paso, Texas, to join her husband, who is an astrophysicist.

Denver, which was in the middle a heat wave at the time, was reporting temperatures in the 90s at the airport.

Crew members allowed her and the baby to leave the aircraft for 20 minutes. When they were called back for takeoff, the plane was delayed again. This time, she claims she was not allowed off the plane, which was delayed again with passengers on the tarmac.

In total, she says she was on the hot plane for two hours.

The flight crew showed concern when they allowed her to stand with her baby at the open door of the plane. They also brought over bags of ice.

Suddenly, she says, "his whole body flashed red and his eyes rolled back in his head and he was screaming and then he went limp in my arms. It was the worst moment of my life. I really thought my son was going to die in my arms."

The crew called for an ambulance and Owen was rushed to the hospital.

France later said the airline "seemed completely unprepared for a medical emergency."